Vapor compression systems may allow operations with heating and/or cooling cycles. Vapor compression systems may comprise two heat exchangers, a compressor, and/or valves coupled together with tubing to form a refrigerant circuit. Vapor compression systems may further comprise other components, such as fans that blow air across the two heat exchangers.
Heat pumps of air conditioning systems may be vapor compression systems that may allow operations with heating and cooling cycles. During a cooling cycle of the heat pump, cool air may be provided by blowing air (e.g., from a fan) across a first heat exchanger (e.g., indoor coil) that acts as an evaporator to evaporate liquid refrigerant. A temperature and/or humidity of the air may be reduced and the cool air may be provided to a location, such as a home, for example. Moisture removed from the air may collect on the evaporator (e.g., as liquid flowing to a drain pan). The gaseous refrigerant may exit the first heat exchanger, be compressed by a compressor, and then delivered to a second heat exchanger (e.g., outdoor coil) acting as a condenser. The second heat exchanger may condense the gaseous refrigerant, for example by allowing air blowing across the second heat exchanger to remove heat from the gaseous refrigerant.
To allow the heat pump to operate in a heating cycle, the heat pump system may include a reversing valve to allow the refrigerant to flow in the opposite direction as the refrigerant flow in the cooling cycle. For example, hot air may be provided by blowing air across the first heat exchanger (e.g., indoor unit), which acts as a condenser (e.g., the air may remove heat from the refrigerant and allow the refrigerant to condense). The hot air may be provided to a location by the system. The second heat exchanger (e.g., outdoor unit) may act as an evaporator and the temperature of the air may be cooler when leaving the second heat exchanger than when entering the second heat exchanger. When outdoor ambient temperatures are cold, the temperature of the second heat exchanger (e.g. outdoor unit and evaporator) may drop below freezing, such that moisture removed from the air may accumulate as frost on one or more surfaces of the second heat exchanger.
Another type of vapor compression system is a refrigeration system, which operates in a similar manner to a heat pump during a heating cycle. In a refrigeration system, cooling is provided to a refrigerated compartment (e.g. a walk-in cooler) by blowing air (e.g. from a fan) across a first heat exchanger that acts as an evaporator to evaporate liquid refrigerant. A temperature of the air may be reduced and the cool air may be provided to a location (e.g. at least a portion of the refrigerated compartment). Since the ambient air temperature within a refrigerated compartment is generally cold, the temperature of the air flowing over the first heat exchanger (e.g. evaporator) may drop below freezing, such that moisture removed from the air may accumulate as frost on one or more surfaces of the second heat exchanger.